Electrical apparatus



Nov. 11, 1941. WHWTAKER l 42,262,414

ELECTRICAL APPARATUS F'iled Nov. 29, 1939 WITNESSES: y INVENTOR Chaz/les C. W itakel? Qww//L `on `the other contact member.

Patented Nov. 11, 1941 ELECTRICAL APPARATUS Charles (LWhittaker, Pittsburgh, Pa., assignor lto Westinghouse Electric & Manufacturing C'ompany, lEast Pittsburgh, 'iP-a., a, corporation of Pennsylvania Application .November 29, 1939, 4Serial. No. 303,660

10 Claims. k(C1. 20044-113) This invention relates to electrical apparatusl and particularly 4to switching apparatus =of the vibratory type such as is used in voltage regulators.

In ,vibrating regulators, it is -found that vthe x.

contact lmembers develop a high resistance contactsurface. Upon examinatiomit is found that this high .resistance surface is developed by-a ,deposit of material from one contact memberzon rto the other'to such-an extent that pinnacles are .formed on the contact surface. It is thought that these `pinnacles are formedby reason that the contact members always vmate on a corresponding point with the result that a pinnacle is formed on one contact while a valleyis formed With such pinnacles formed on the `contactsurface of the contactmembersif the contactmembers are-moved, it .is possible that two of `the pinnacles will -mate giving a ypoint of extremely high resistance on the contact surface, with theresult that .the contact members have `to have their contact surfaces redressed quite frequently.

An object of this invention `is to providefor increasing the life of the contactmembers of ra switching apparatus.

Another object of this linventionisto provide a switching `apparatus having a .contact ,member so mounted as to prevent movement `of its conltact surface out of a fixed plane, while permitting movement inthe fixed plane relative vto Na contact member which is disposed to be actuated into and out of engagement therewith. lA further object of this invention is to provid a switching apparatus having a contact member mounted in a iixed plane anda contact member disposed to be actuated into and out of engagement therewith, the mounted contact being .actuated by a bimetal elementto move, in the xed plane to different positions relative to the other contact member.

Other objects of this invention wil1become apparent from the following description, when taken in conjunction with the accompanying drawing, in which Figure 1 is a view in side elevation of a rregulatorembodying the teachings of this invention; Fig. 2 is an end view of the regulator illustrated in Fig. 1;

Fig. 3 is a bottom plan view'of the left-hand ,secured in position as by the screws 20.

`Referring to the drawingfa supporting panel I0 is .provided upon which is mounted a core structure I2 comprising a winding leg yI4 extend- .ingfbetween two lateral core legs I6 and I8 and The Ycore structure I2 is securely mounted on the panel I0 by means of the screws 22 shown in Fig. AZ. In addition to the core legs I6.and I8, the core `also includes .a .portion 24 attached to the leg I6 by means of the screw 26 and which terminates a vdistance spaced =from the adjacentend of theleg ltoprovide a space therebetween for accommodating an armature 28 of magnetic material mounted kon a lever 38 of non-magnetic material. A movable Contact member 32 comvprising a two-faced contact member, as illustrated, .is mounted upon the upper end of the llever 30 and is adapted to engage either contact member 34 .or 36 which are mounted on the panel IIJ., as will `be explained hereinafter.

In order to provide a pivot for the lever 30, a block 38 havinga lower corner beveled, as at 40, is attached to the side of the lever 30 in position opposite a similar bevel 42 on the end of the leg rI6 of the core structure and is attached tothe core structure I2 through a Yplurality Vof iiat springs .44 and 46 `disposed at .right angles vto each otherand attached tothe block 38 by screws 48 and 50, respectively, and to the leg I6 by screws .26 Aand 52, respectively. These fiat springs, usually two springs of each of 44and ,.476

spaced apart, form a pivot or hinge for the lever 30 about the axis along the intersection of the Aplane of thesprings, as shown, about which the movable structure can pivot.

As illustrated, the winding leg I4 carries an operating winding 54 kdisposed between the legs I 6 andk I8 for energizing the magnetic circuit. In order to cause the -center of gravity of the movable ,element to coincide with the pivotal axis 'formed bythe springs 44 and 46, a counterweight '56 is provided at the lower end of the lever 30 and secured thereto as by means of screws 58 In order to adjust the tension on the lever 30,

7 an adjustable helical spring 60 is provided having one end `attached to a bracket 62 mounted on the panel I0 and the otherend attached to the lever 30`through an adjustable securing device 64 having vset screws V66 and A68 for laterally adjusting the tension of the spring 60.

` As illustrated, the movable contact member 32 isppositioned to engage either contact member 34 or 36 which are provided having contact surfaces .in Iixedparallelplanes disposed in denite spaced .relation to leach other. These contact members are similarly mounted on the panel |0. In Order to provide for movement of the contact member 34 in a fixed plane parallel to the plane of the contact surface of contact 32 while remaining stationary with respect to the fixed distance between the stationary contact members 34 and 36, the contact members 34 and 36 are each mounted on the panel I by means of a bimetal support 10.

Referring particularly to Figs. 2 and 3, the support for contact member 34 comprises two bimetal members 1.2 and 14, the bimetal member 12 being of substantially U-shape having one leg longer than the other while the bimetal mem-r ber 14 is of substantially L-shape. These bimetal members are mounted on the panel I0 with one leg of each of the bimetal elements overlapping and are secured to the panel as by means of the screws 16. As illustrated, the bimetal member 12 carries a substantially U-shaped bracket member 18 for supporting the contact member 34. One of the legs 19 of the bracket member 18 is so secured to the longer leg of the bimetal member 12 by ymeans of the screws 80, as to position the center portion of the bracket 18 for forming the contact carrying face of the support 10. In

'this position the contact carrying face of the bracket 18 is disposed in a plane which cuts the bimetal members at substantiallv right angles along their longest dimensions. Thus, the contact carrying face of the bracket 18 is in a plane parallel to the plane through which the bimetal elements expand when heated, as referred to hereinafter. The direction of the expansion of the bimetal members will be such as to tend to straighten the bimetal members or to bend them depending upon which side of the individual bimetal member is the high expansion component of the member. For illustrating this invention, the bimetal members are positioned with the high expansion component adjacent the contact member 34 so that when heated the bimetal members will tend to straighten and thereby move farther apart.

In the embodiment illustrated in Figs. 2 and 3, when the U-shaped bracket member 18 is mounted in assembled relation with the bimetal mem,- ber 12. the other leg 82 of the bracket 18 extends away from the contact carrying face and has its outer edge in4 abutting engagement with a stop 84. 'I'he stop 84 is of substantially L-shape and is so secured to the base or overlapped portion of the bimetal elements 12 and 14 and to the panel I0 by means of the screws 1.6 as to have one of its legs project outwardly from the base portion to engage the leg 82 and prevent movement of the U-shaped bracket 18 out of the fixed plane, as will be explained more fully hereinafter.

The contact member 34 is carried by the U- Vshaped bracket 18 being secured thereto by means of the screw 86. 'As more clearly illustrated in Fig. 2, the legs of the bimetal members 12 and 14 opposite their overlapped and secured ends vare interlocked, the bimetal member 14 having with respect to each other is in a fixed plane, the line of movement of the members as they tend to straighten when heated being in a plane which passes through the longest dimensions of the bimetal member and which is parallel to the desired fixed plane of the contact surface of contact member 34. This interlocked joint between the bimetal members 12 and 14 prevents torsional movement of the bimetal support for the contact member 34. It is, of course, to be understood that the bimetal support described with respect to the contact member 34 is duplicated for the contact member 36, the support for the contact member 36 comprising the elements of the support described except that they are mounted in the reverse order.

Referring to Fig. 4, a generator 92 is provided having an armature winding 94 connected to circuit conductors 96 and 98 and a field Winding |00 that is connected between a junction point |02 on the conductor 96 through a resistor |04 to a junction point |06 on the conductor 98. The movable contact member 32 of the regulator is connected to ajunction point |08 between the field winding |00 and resistor |04. The regulator contact member 34 is connected through the bimetal support 10 and conductor ||0 to the junction point |02 on conductor 96, while the regulator contact member 36 is connected through the other bimetal support 10, conductor ||2, to the junction point |06 on conductor 98. The regulator winding 54 is connected to be energized in accordance with the voltage between conductors 96 and 98, as illustrated.

The tension of the spring 60 is adjusted to accord with the voltage desired to be maintained between conductors 96 and 98. This spring normally biases the Contact member 32 into engagement with the contact member 36 to shunt the resistor |04 from the circuit of the field winding 00. As the voltage of the generator armature 94 increases, the current through the generator field winding |00 and the regulator also increases until the energization of the winding 54 increases sumciently that the pull on the armature 28 becomes sufiicient to overcome the pull of the spring 60, thus moving the armature 28 in a counterclockwise direction about the pivot formed by the springs 44 and 46 against the pull of the spring 60 to separate the Contact member 32 forming the contact member 36. This introduces the resistor |04 in circuit with the field winding |00 between conductors 96 and 98, decreasing the energization of the generator and causing the voltage thereof to decrease. The decrease in the energization of the winding 54 causes the pull on the armature 28 to decrease sufficiently that the force of the spring 60 moves the armature 28 in ay clockwise direction and causes engagement of the contact member 32 with the contact member 36. The regulator is sufliciently sensitive that the repeated engagement of the contact member 32 with the contact member 36, and separation therefrom, takes place at such a rapid rate that the voltage between the conductors 96 ,and 88 does not vary appreciabiy from the desired tinue until the counterclockwise movement thereof is sufficient to cause the contact member 32 cuit the field Winding |00. tThe continued vibrations of the regulator will, under this condition,

cause repeated rengagement of the contact member 32 with, and 'separation from, the contact member 34 instead of with and from the contact member 36.

In all 'these operations described hereinbefore, each of the bimetal'supports 10 for supporting the contact `member 34 and the contact member 36 is in circuit With the contact member which it supports, so'that when the movable contact member 32 engages ,either the contact member 34 or 36, current passes directly through the bimetal support 1U of the contact member engaged. As will readily be appreciated, the 12R losses in the bimetal due to the passage of the current through the bimetal will so heat the bimetal members that when they expand they tend to straighten and move with respect to each other in the xed plane parallel to the plane of the contact surface of contact member 34 or 36. The movement of the :bimetal members 12 and 14 effects a, movemerit of the contact member 34 or 36 so as to vary the position of the contact surface of the contact member in its initially fixed plane. Where the movable contact member 32 isengaging either one of the contact members 34 or 36, it is found that the heat conducted into the bimetal from the contact or changes in the ambient temperature is sufficient to effect a movement of the bilmetal support and consequently of the contact member supported thereby. Thus as the contact member 32 is rapidly vibrating between the contact members 34 and 36 or into engagement with either of the contact members 34 and 36. it is evident that due to thecharacteristics of the bimetal support, the contact member initially mounted in a fixed plane with respect to the contact member 32 is constantly varying its position in the fixed plane to vary the point contacts between the contact member 32 and the contact member which it is actuated to engage.

Although the nterlocked` ends of the bimetals 12 and 14 prevent torsional movement of the bimetal members during the operation thereof and the bmetals aremountedon edge as'illustrated in Figs. 2 and 3, so that movement perpendicular to the initially fixed plane is substantially impossible, it is evident from the provision of the stop 84 that means is provided whereby it is impossible to move the contact member 34 or the similarly mounted contact member 36 out of its initially xed plane even under the contact pressures developed when the contact member 32 is actuated into engagement therewith, the stop 84 effectively preventing all movement except that in the xed plane as initially determined. In practice, where contact members are mounted on the bimetal supports, it is found that approxi- -mately lz of an inch of motion is obtained in the fixed plane oi' the contact surface of contact members 34 and 36 for a change in temperature of 35 F. Such motion of the contact members in the fixed plane aids in keeping the contact surfaces flat and prevents formation of irregularities on the surfaces, thereby prolonging the life of the contact members.

Although this invention has been described with reference to a particular embodiment thereof, it is intended that all mattersrcontained in the description given hereinbefore shall be interpreted as illustrating and not in a limiting sense.

I claim as ymy invention: 1. In a switching apparatus, the combination comprising, a first contact member, a second contact member disposed to be actuated into and out of engagement with the first contact member, jthe first contact member having a contact surface in a xed plane, and means for supporting the rst contact member to maintain its contact sui'- `face in the fixed plane, said means being responsive to predetermined thermal conditions to actuate thev first contact member to vary the position 'of its contact surface .in the fixed plane with `respect vto the second contact member.

tact member disposed to be actuated into and` out of engagement with the first contact member,

Athe first contact member having a contact surface in a fixedplane, and means for supporting the first contact member to maintain its contact surface in the fixed plane, said means actuating the first contact member under predetermined conditions to vary the position of its contact surface Ain the xed plane with respect to the second contact member.

3. In a switching apparatus, the combination comprising, a rst contact member, a second contact member disposed to be actuated into and out of engagement with the first contact member, each ofthe contact members having contact surfaces disposed in parallel planes when the contact `members are in engagement, the contact surface of the first contact member being in a fixed plane at all times, and a support including a` bimetal member for retaining the first contact member in the fixed plane, the bimetal member under predetermined conditions actuating the yfirst contact member to different positions in the lfixed plane relative to the second contact member.

4. In a switching apparatus, the combination comprising, a first contact member, a second contact member disposed to be actuated into and out of engagement with the first contact member, Vthe first contact member having a contact surface in a fixed plane, and a support including 'a plurality of bimetal members for carrying the rst contact member, the bimetal members being -interlocked to prevent torsional movement thereof and vto insure `movement of the contact member carried thereby in the fixed plane under predetermined conditions whereby the first contact member presents different contact points for different operations when the second contact member is actuated into engagement therewith.

5. In a switching apparatus, the combination comprising, a first contact member having a contact surface, a second contact member disposed to be actuated into and out of engagement with the first contact member, and means for supporting the iirst contact member to maintain its contact surface in a xed plane, the supporting means including a bimetal member disposed for movement under predetermined conditions, means for securing the rst contact member to the bimetal member whereby the first contact member moves in response to movement of the bimetal member, and means associated with the bimetal member for limiting movement of the first contact member to the fixed plane.

6. In a switching apparatus, the combination comprising, a first contact member having a contact surface in a fixed plane, a second contact member disposed to be actuated into and out of engagement with the first contact member,

and means for supporting the firstcontact member to maintain its contact surface in a fixed plane while permitting movement of the first contact member to vary the position of its contact surface in the iixed plane with respect to the second contact member, the supporting means including a pluralityof bimetal members disposed for movement in a fixedplane in response to predetermined conditions, means for securing the first contact member to one of the bimetal members whereby it moves in response to movement of the bimetal members, and a stop disposed to cooperate with the securingy means to prevent movement of the first contact member from. the xed plane under contact pressure of the second contact member when it is actuated into engagement therewith.

7. In a switching apparatus, the combination comprising a first contact member having a contact surface in a fixed plane, a panel for carrying the first contact member, a second contact member disposed to be actuated intoand out of engagement with the first contact member, and means for supporting the first contact member to maintain its contact surface in a fixed plane while permitting movement of the first contact member to vary the position of its contact surface in the fixed plane with respect to thesecond contact member, the supporting means including a plurality of bimetal members disposed for movement in response to predetermined conditions, one of the bimetal members being substantially U-shaped, the other of the bimetal members being substantially L-shaped, a leg of each of the bimetal members being overlapped and secured to the panel, the other legs of the bimetal members being interlocked whereby the members are positioned for movement in a plane parallel to the fixed plane, means for securing the first contact member to the U-shaped bimetal member to obtain a movement of the first contact member in response to movement of the bimetalmember, a stop disposed to cooperate withk the securing means to prevent movement of the first contact member from the fixed plane member when it is actuated into engagement therewith.

8. In a'switching apparatus of the vibratory type, the combination comprising, a plurality of contact members disposed in spaced relation having their contact surfaces in parallel fixed planes,

a contact member positioned between the spaced contact members and disposed to be actuated intol or out of engagement with either of them,

to the panel, means for mounting the contact 1.5 under contact pressure of the second contact member on the bimetal member, and means associated with the bimetal member to retain the contact surface of the contact member iny its fixed plane, the bimetal member under predetermined conditions actuating the contact member carried thereby for effecting movement of the contact memberin the fixed plane with respect to the contactmember positioned between the spaced contact members.`

9. In a switching apparatus,.the combination comprising, a first contact member, a second contact member disposed to be actuated into and out of engagement with the first contact member, the first contact member having a contact surface in a fixed plane, means for supporting the first contact member to maintain its contact surface in the xed plane, saidmeans actuating the first contact member under predetermined conditions to vary the position of its contact'surface inthe fixed pla-ne with respect to the second contactmember, and a stop disposed to cooperate with said supportingy means to prevent movement ofthe first Contact member from the fixed plane under contact pressure of the second contact member when it is actuated into engagement therewith. c

10. In a switching apparatus, the combination comprising, a rst contact member, a second contact member disposed to be actuated into and out of engagement with the first contact member, the first contact member having a contact surface in a fixed plane, land a support including a bimetal member disposed for movementunder predetermined conditions for carrying the first contact member, means associated with the bimetal member disposed to prevent torsional movement thereofvand to insure movementof the contact member carried thereby in the fixedA plane whereby the first contact member presents different contact points for different operations when the second contactV member is actuated into engagement therewith.

CHARLES C. WI-HTTAKER. 

